Department of Bioengineering, University of Washington, Seattle, Washington, United States.
Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States.
Invest Ophthalmol Vis Sci. 2024 Jun 3;65(6):26. doi: 10.1167/iovs.65.6.26.
In age-related macular degeneration (AMD), choriocapillaris flow deficits (CCFDs) under soft drusen can be measured using established compensation strategies. This study investigated whether CCFDs can be quantified under calcified drusen (CaD).
CCFDs were measured in normal eyes (n = 30) and AMD eyes with soft drusen (n = 30) or CaD (n = 30). CCFD density masks were generated to highlight regions with higher CCFDs. Masks were also generated for soft drusen and CaD based on both structural en face OCT images and corresponding B-scans. Dice similarity coefficients were calculated between the CCFD density masks and both the soft drusen and CaD masks. A phantom experiment was conducted to simulate the impact of light scattering that arises from CaD.
Area measurements of CCFDs were highly correlated with those of CaD but not soft drusen, suggesting an association between CaD and underlying CCFDs. However, unlike soft drusen, the detected optical coherence tomography (OCT) signals underlying CaD did not arise from the defined CC layer but were artifacts caused by the multiple scattering property of CaD. Phantom experiments showed that the presence of highly scattering material similar to the contents of CaD caused an artifactual scattering tail that falsely generated a signal in the CC structural layer but the underlying flow could not be detected. Similarly, CaD also caused an artifactual scattering tail and prevented the penetration of light into the choroid, resulting in en face hypotransmission defects and an inability to detect blood flow within the choriocapillaris. Upon resolution of the CaD, the CC perfusion became detectable.
The high scattering property of CaD leads to a scattering tail under these drusen that gives the illusion of a quantifiable optical coherence tomography angiography signal, but this signal does not contain the angiographic information required to assess CCFDs. For this reason, CCFDs cannot be reliably measured under CaD, and CaD must be identified and excluded from macular CCFD measurements.
在年龄相关性黄斑变性（AMD）中，可以使用已建立的补偿策略来测量软性玻璃膜疣下的脉络膜毛细血管血流缺损（CCFDs）。本研究旨在探讨CCFDs 是否可以在钙化玻璃膜疣（CaD）下进行定量评估。
本研究共纳入了 30 只正常眼、30 只软性玻璃膜疣 AMD 眼和 30 只 CaD AMD 眼。生成 CCFD 密度掩模以突出 CCFD 较高的区域。掩模也是基于结构型横断面 OCT 图像和相应的 B 扫描，同时针对软性玻璃膜疣和 CaD 生成。计算 CCFD 密度掩模与软性玻璃膜疣和 CaD 掩模之间的 Dice 相似系数。进行了一项幻影实验，以模拟源自 CaD 的光散射的影响。
CCFD 的面积测量结果与 CaD 的高度相关，但与软性玻璃膜疣无关，这表明 CaD 与下方 CCFD 之间存在关联。然而，与软性玻璃膜疣不同，CaD 下检测到的光学相干断层扫描（OCT）信号并非源自定义的脉络膜毛细血管层，而是源自 CaD 的多重散射特性的伪影。幻影实验表明，存在与 CaD 内容相似的高散射物质会产生人为的散射尾部，从而在脉络膜毛细血管结构层中产生虚假信号，但无法检测到下方的血流。同样，CaD 也会产生人为的散射尾部，并阻止光线穿透脉络膜，导致在脉络膜面下发生低透射缺陷，无法检测到脉络膜毛细血管内的血流。在解决 CaD 后，CC 灌注变得可检测。
CaD 的高散射特性导致这些玻璃膜疣下产生散射尾部，从而产生可量化的光学相干断层扫描血管造影信号的错觉，但该信号不包含评估 CCFD 所需的血管造影信息。因此，在 CaD 下无法可靠地测量 CCFD，必须识别并排除 CaD 以进行黄斑 CCFD 测量。
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